FIG. 8A and FIG. 8B provide a heat pump as is described in European Patent EP 2016349 B1. The heat pump initially includes an evaporator 10 for evaporating water as a working liquid so as to generate vapor within a working vapor line 12 on the output side. The evaporator includes an evaporation space (evaporation chamber) (not shown in FIG. 8A) and is configured to generate an evaporation pressure smaller than 20 hPa within said evaporation space, so that at temperatures below 15° C. within the evaporation space, the water will evaporate. The water is, e.g., ground water, brine, i.e. water having a certain salt content, which freely circulates in the earth or within collector pipes, river water, lake water or sea water. Any types of water, i.e. limy water, lime-free water, salty water or salt-free water, may be used. This is due to the fact that any types of water, i.e. all of said “water materials” have the favorable water property that water, which is also known as “R 718”, has an enthalpy difference ratio of 6 that can be used for the heat pump process, which corresponds to more than double the typical enthalpy difference ratio of, e.g., R134a.
Through the suction line 12, the water vapor is fed to a compressor/condenser system 14 comprising a fluid flow machine (turbo-machine) such as a radial compressor, for example in the form of a turbocompressor, which is designated by 16 in FIG. 8A. The fluid flow machine is configured to compress the working vapor to a vapor pressure at least larger than 25 hPa. 25 hPa corresponds to a condensation temperature of about 22° C., which may already be a sufficient heating flow temperature of an underfloor heating system. In order to generate higher flow temperatures, pressures larger than 30 hPa may be generated by means of the fluid flow machine 16, a pressure of 30 hPa having a condensation temperature of 24° C., a pressure of 60 hPa having a condensation temperature of 36° C., and a pressure of 100 hPa having a condensation temperature of 45° C. Underfloor heating systems are designed to be able to provide sufficient heating with a flow temperature of 45° C. even on very cold days.
The fluid flow machine is coupled to a condenser 18 configured to condense the compressed working vapor. By means of the condensing process, the energy contained within the working vapor is fed to the condenser 18 so as to then be fed to a heating system via the advance 20a. Via the backflow 20b, the working liquid flows back into the condenser.
In accordance with the invention, it is advantageous to directly withdraw the heat (energy), which is absorbed by the heating circuit water, from the high-energy water vapor by means of the colder heating circuit water, so that said heating circuit water heats up. In the process, a sufficient amount of energy is withdrawn from the vapor so that said stream is condensed and also is part of the heating circuit.
Thus, introduction of material into the condenser and/or the heating system takes place which is regulated by a drain 22 such that the condenser in its condenser space has a water level which remains below a maximum level despite the continuous supply of water vapor and, thus, of condensate.
As was already explained, it is advantageous to use an open circuit, i.e. to evaporate the water, which represents the heat source, directly without using a heat exchanger. However, alternatively, the water to be evaporated might also be initially heated up by an external heat source via a heat exchanger. In addition, in order to also avoid losses for the second heat exchanger, which has expediently been present on the condenser side, the medium can also used directly, and for example when one thinks of a house comprising an underfloor heating system, the water coming from the evaporator can be allowed to directly circulate within the underfloor heating system.
Alternatively, however, a heat exchanger supplied by the advance 20a and exhibiting the backflow 20b may also be arranged on the condenser side, said heat exchanger cooling the water present within the condenser and thus heating up a separate underfloor heating liquid, which typically will be water.
Due to the fact that water is used as the working medium and due to the fact that only that portion of the ground water that has been evaporated is fed into the fluid flow machine, the degree of purity of the water does not make any difference. Just like the condenser and the underfloor heating system, which is possibly directly coupled, the fluid flow machine is supplied with distilled water, so that the system has reduced maintenance requirements as compared to today's systems. In other words, the system is self-cleaning since the system only ever has distilled water supplied to it and since the water within the drain 22 is thus not contaminated.
In addition, it shall be noted that fluid flow machines exhibit the property that they—similar to the turbine of a plane—do not bring the compressed medium into contact with problematic substances such as oil, for example. Instead, the water vapor is merely compressed by the turbine and/or the turbocompressor, but is not brought into contact with oil or any other medium impairing purity, and is thus not soiled.
The distilled water discharged through the drain thus can readily be re-fed to the ground water—if this does not conflict with any other regulations. Alternatively, it can also be made to seep away, e.g. in the garden or in an open space, or it can be fed to a sewage plant via the sewer system if this is stipulated by regulations.
Due to the combination of water as the working medium with the enthalpy difference ratio, the usability of which is double that of R134a, and due to the thus reduced requirements placed upon the closed nature of the system and due to the utilization of the fluid flow machine, by means of which the compression factors that may be used are efficiently achieved without any impairments in terms of purity, an efficient and environmentally neutral heat pump process is provided.
FIG. 8B shows a table for illustrating various pressures and the evaporation temperatures associated with said pressures, which results in that relatively low pressures are to be selected within the evaporator in particular for water as the working medium.
DE 4431887 A1 discloses a heat pump system comprising a light-weight, large-volume high-performance centrifugal compressor. Vapor which leaves a compressor of a second stage exhibits a saturation temperature which exceeds the ambient temperature or the temperature of a cooling water that is available, whereby heat dissipation is enabled. The compressed vapor is transferred from the compressor of the second stage into the condenser unit, which consists of a granular bed provided inside a cooling-water spraying means on an upper side supplied by a water circulation pump. The compressed water vapor rises within the condenser through the granular bed, where it enters into a direct counter flow contact with the cooling water flowing downward. The vapor condenses, and the latent heat of the condensation that is absorbed by the cooling water is discharged to the atmosphere via the condensate and the cooling water, which are removed from the system together. The condenser is continually flushed, via a conduit, with non-condensable gases by means of a vacuum pump.
WO 2014072239 A1 discloses a condenser having a condensation zone for condensing vapor, that is to be condensed, within a working liquid. The condensation zone is configured as a volume zone and has a lateral boundary between the upper end of the condensation zone and the lower end. Moreover, the condenser includes a vapor introduction zone extending along the lateral end of the condensation zone and being configured to laterally supply vapor that is to be condensed into the condensation zone via the lateral boundary. Thus, actual condensation is made into volume condensation without increasing the volume of the condenser since the vapor to be condensed is introduced not only head-on from one side into a condensation volume and/or into the condensation zone, but is introduced laterally and, advantageously, from all sides. This not only ensures that the condensation volume made available is increased, given identical external dimensions, as compared to direct counterflow condensation, but that the efficiency of the condenser is also improved at the same time since the vapor to be condensed that is present within the condensation zone has a flow direction that is transverse to the flow direction of the condensation liquid.
What is generally problematic about heat pumps is the fact that movable parts and, in particular, fast-moving parts are to be cooled. What is particularly problematic here are the compressor motor and, specifically, the motor shaft. Specifically for heat pumps for which radial impellers are used as the compressors, which radial impellers are operated very fast, e.g. within ranges larger than 50,000 revolutions per minute, in order to achieve a small design, shaft temperatures may reach values which are problematic since they may result in destruction of the components.